Diodes are electronic elements capable of conducting current, in response to a voltage potential placed across the diode, in one direction only. As such, these elements are widely used in electronic applications, such as current rectification and signal gating.
Diodes may be designed to respond to various environmental conditions, such as temperature, electromagnetic radiation, or magnetic fields, and in this capacity, the diode may function as a sensor of the diode-response condition. It would be desirable to extend the range of diode response to a variety of chemical and biological conditions, such as pH, the salt concentrations, and the presence or absence of specific binding agents, such as biological analytes.
It would also be desirable to provide a miniature (micron-scale) diode element capable of swelling and contracting rapidly in response to voltage changes across the element, for use in constructing miniature devices such as pumps and mechanical actuators.